As society is becoming increasingly mobile, we see the rapid adoption of mobile phones, laptop computers, palm devices, personal stereos, remote controllers and as any parent knows, a huge array of electronic toys. Batteries are the power source of necessity for these devices which have become an everyday part of life whether at work, at home and at play.
The prior art illustrates a strong lack of options delivering efficiency and effectiveness and fails to provide a convenient and cost effective solution. Currently, the consumer is expected to merely purchase a new battery every time a battery goes out.
Many people take up rechargeable batteries so that the batteries can be recharged and reused over and over again. The disadvantages of rechargeable batteries are that they cost much more than primary batteries and replacing the whole house with a rechargeable system would be out of the question for most people. Further, rechargeable batteries lose their effectiveness and, in particular, their period of time ‘in use’ decreases and they are therefore required to be charged more frequently over time.
In addition, rechargeable batteries are rendered unsuitable for many electronic applications as rechargeable batteries have a very fast self discharge rate compared to primary alkaline batteries.
Further, a recharging battery requires a complicated battery charger which adds further cost to the consumer and can be quite difficult or complicated to operate. In addition, when the battery goes flat recharging requires an external power source, such as a power outlet. When the battery is not charged effectively, it is cumbersome and impractical to locate a power source when mobile or in transit.
There is a complex number and variety of battery types available on the market that includes rechargeable nickel cadmium and nickel metal hydride batteries as well as primary carbon zinc, alkaline and rechargeable alkaline batteries. Adding further to the complexity and confusion of rechargeable and non-rechargeable batteries are new alkaline variants called Titanium and long lasting advanced formula batteries and so forth that truly making recharging batteries a mine field for many people.
For one reason or the other, primary alkaline batteries still remain a part of our everyday life. They are readily available everywhere and their toxic wastes continue to threaten landfills and waterways. Many attempts have been made to come up with systems that can recharge primary alkaline as well as rechargeable batteries to help save money and the environment. Up until now, all recharger systems available are at their infancy stage and suffer from a wide range of short comings that made them unreliable and/or unsafe to use. Clearly there is a need to come up with a multi-chemistry battery recharging system that can overcome most if not all of the short-comings known that are reliable and safe for consumer use.
Several prior art disclosures suggest different means for discriminating between primary and secondary batteries. One method disclosed the measurement and use of internal battery resistances to distinguish between primary alkaline and secondary NiCd batteries as outlined in U.S. Pat. No. 5,600,224. However this method is not reliable as consumer batteries are becoming complicated in recent time with more battery types added to the list such as the addition of the new breed of advanced formula alkaline batteries with very low internal resistances and the environmentally, more friendlier, NiMH and rechargeable alkaline batteries which make the distinguishing line not so apparent. Furthermore as batteries age, their internal resistances become higher and the values overlap one another which make this distinguishing task using internal resistances even more unreliable.
The most commonly seen method employed in chargers, charge only batteries having a certain predetermined feature. These however are not entirely satisfactory from the combined standpoints of safety, ease of use and more importantly these do not meet the criteria to be considered as universal recharging system that accepts most chemistry types of batteries.
Also, commonly seen approaches use mechanical or electronic switch selections as a means to distinguish the two battery types and thereafter apply a low charge current to primary alkaline batteries and moderate charge current to rechargeable batteries. These systems rely on the users to make complicated and often confusing selections that could lead to wrong operating settings either through plain human errors or technical ignorance. The consequences of such errors would cause adverse battery leakage, damage to batteries and chargers and, in worst cases, lead to dangerous battery explosions. Another short coming using this approach is that the system cannot charge different mix of batteries simultaneously. This type of chargers usually only can charge single battery type at a time.
Further, in practice there is the use of a common low charge current safely recharging both types of batteries so they can co-exist within a single charging system. This is the closest system that can overcome many problems encountered previously and is safe to use. However there are shortcomings with this technique as well as it taking at least 15 hours or more to charge up primary alkaline and rechargeable batteries. Even with the lengthy charge time, this system still cannot fully charge up many high capacity rechargeable NiMH batteries.
So there is a need to come up with a more efficient and effective method to automatically detect and distinguish primary and secondary dry-cell batteries without any involvement of the error-prone user interaction described above. There is also a further need for a faster and improved charging method that can properly recharge most different battery types within a single system.
The present invention attempts to overcome or at least ameliorate one or more of the problems of the prior art and to achieve or at least progress towards achieving one or more of the following objects of the invention.
It is therefore an object of the present invention to provide a charger that is capable of identifying primary non-rechargeable and secondary rechargeable dry-cell batteries.
It is another object of the present invention to provide a charger that is capable of safely recharging the widest range of different consumer battery types that belong to both groups of primary and secondary dry-cell batteries simultaneously.
It is yet another object of the present invention to provide a charger that can accommodate several different sizes, namely AAA, AA, C, D, Prismatic or gum-stick, 9V and N-sized batteries. The same charger can also further be expanded to include extra facilities to power a range of otherwise unpowered devices or charge up different battery packs in many self-powered devices.
It is still yet another object of the present invention to provide a charger that is very easy to use and requires little or no battery knowledge from the user.
It is also another object of the present invention to provide a charger that can deliver different rates of fast and slow charging to the batteries with multiple charge termination schemes and multiple safety protection capabilities.
It is also yet another object of the present invention to provide a charger that shows detailed information of the battery conditions and charging status that are easily understood.